The invention relates to a fuel filter with an internal water accumulation chamber which communicates with a water outlet provided in the filter housing enclosure and a water discharge valve arranged at the water outlet.
DE 198 04 549 discloses a fuel filter, particularly for diesel fuel, which is formed by a filter housing with an inlet connection and an outlet connection. Inside the housing, a filter element is arranged, which separates an unfiltered side from a filtered side to form a seal. In the lower part of the housing, a water collection chamber is provided to take up water removed from the fuel. A water sensor protrudes into this water collection chamber. The water may be removed from the water collection chamber via a valve that is externally actuated by mechanical means and opens or closes a water outlet. The valve is arranged on the housing floor and is actuated by a cable assembly, which is disposed outside the filter housing in the area of the housing floor.
The disadvantage of this embodiment is that the valve requires space outside the filter housing. The space available to install a fuel filter in a motor vehicle is limited and is generally substantially filled by the filter housing. In addition, the cable assembly needs a moving mechanism, which also requires installation space. Furthermore, the valve is formed by many separate parts, which makes it costly to produce.
It is the object of the invention to provide a fuel filter with a water outlet.
Another object of the invention is to provide a fuel filter which can be installed in a small installation space.
A further object of the invention is to provide a fuel filter with a water discharge which can be manufactured economically.
These and other objects have been achieved in accordance with the present invention by providing a fuel filter suitable for filtering diesel fuel comprising a filter housing comprising a filter head and a housing enclosure, a fuel inlet and a fuel outlet arranged on the filter housing, and a water accumulation chamber which communicates with a water outlet provided in the housing enclosure, a cylindrical filter element installed in the filter housing such that an unfiltered side of the filter which communicates with the fuel inlet is sealingly separated from a filtered side of the filter which communicates with the fuel outlet, and a water discharge valve at the water outlet with an actuator for opening the water discharge valve from outside the filter, wherein the actuator is connected to the filter head on the one hand and the water outlet on the other hand.
The fuel filter according to the invention serves to clean a fuel, particularly diesel fuel, in which the water contained in the fuel is separated. To this end, the fuel filter has a filter housing with a filter head and a housing enclosure. The housing parts are connected to one another either permanently, for instance by crimping, or detachably, for instance by a threaded connection. A fuel inlet and a fuel outlet are provided on the filter housing. In special embodiments, the fuel inlet and the fuel outlet are arranged in the filter head. The housing enclosure contains a water accumulation chamber in which the separated water can collect. On the housing enclosure, particularly in the area of the water accumulation chamber, a water outlet is arranged, so that the water accumulation chamber is appropriately connected to the water outlet. The water outlet can be arranged at any location within the housing enclosure. Advantageously the water outlet is disposed at the lowest point of the housing enclosure, so that the water, which collects at the bottom of the enclosure, is very simple to remove from the fuel filter.
The fuel filter comprises a cylindrical filter element with a filter medium. The filter medium can, for instance, be a filter paper or a nonwoven web of filter material. This filter medium can be folded, rolled, or flat. The filter element is introduced into the filter housing such that it separates an unfiltered side from a filtered side and forms a seal. The unfiltered side is connected to the fuel inlet and the filtered side to the fuel outlet. When the filter element is dirty, either the filter element only or the entire fuel filter can be replaced depending on how the filter housing is configured.
The fuel filter further contains a water discharge valve by means of which the water outlet in the housing enclosure can be mechanically opened from the outside via an actuating element. This actuating element is correspondingly connected to the filter head on the one hand and the water outlet on the other hand. The actuating element extends inside the fuel filter, so that no interfering elements are arranged on the outside of the fuel filter. This has the advantage that the fuel filter can be installed in even small and poorly accessible spaces. Further, the water discharge device comprises a sealing element, which can tightly seal the water outlet and which is correspondingly connected to the actuating element and to a moving mechanism by means of which the actuating element can be moved. The moving mechanism can for instance be a pull handle, a lever, a push button, or a ring.
As soon as a certain amount of water has collected in the water accumulation chamber, the moving mechanism is mechanically moved from the outside. This causes the actuating element and the sealing element to move and the water outlet to be unblocked. The actuating element can be moved in a linear or rotary motion. After the water has been removed, the sealing element closes the water outlet again. The point in time when the sealing element closes the water outlet again may be controlled from the outside, e.g., depending on how long the moving mechanism is held in open position. It is also possible, however, to define a time basis that cannot be controlled from the outside or a variable time basis that controls the moving mechanism as a function of environmental influences.
In accordance with a further embodiment of the invention, a water sensor is arranged within the filter housing. This water sensor can be arranged at any point within the filter housing. In a special variant the water sensor is arranged on the enclosure floor or in the filter head. The water sensor is used to determine exactly the time when the water has to be removed from the fuel filter. This eliminates the need to inspect the water level in the fuel filter.
In an advantageous embodiment of the invention, the actuating element extends through a filter interior formed by the cylindrical filter element. This makes it possible to arrange the actuating element at the top of the filter housing and thus simplifies operation. It is advantageous if the water outlet and the actuating element are arranged coaxially to the center axis of the fuel filter. In this embodiment, the actuating element extends through both the filtered side and the unfiltered side, so that suitable measures must be taken to prevent leakage along the actuating element between the unfiltered side and the filtered side. Such suitable measures for preventing leakage include, for example, gaskets connected to the filter element and the actuating element to form a seal. However, the filter element may also be configured in such a way that it fits tightly against the actuating element to form a seal so that any leakage is avoided. However, the actuating element must still be capable of being moved.
It is advantageous that the water outlet can be opened by an axial movement of the actuating element. The actuating element may be embodied as a push rod, which lifts the sealing element from the water outlet and allows the water to flow out. The sealing element, which seals the water outlet from the outside, is pressed against the water outlet with a sufficient biasing force so that the water outlet cannot be opened by excessive internal pressure.
In accordance with a further embodiment of the invention, the water outlet can be opened by pulling on the actuating element. The actuating element is configured in such a way that it can transmit pulling forces. It can for instance be a pull rod or a cable. In this embodiment the sealing element can be arranged in the interior of the fuel filter and be pressed against the water outlet by the liquid in the fuel filter. In this case, only a slight axial movement of the actuating element is required to open the water outlet. The pulling force can for instance be manually applied to the actuating element.
An advantageous variant of the invention provides for a drive unit to produce the axial movement of the actuating element. The actuating element can be moved by a lever mechanism, particularly a rocker or toothed gear. In a lever mechanism, several levers may be used to translate an introduced force into an axial movement. A fixed support point can serve as a reversing point for the introduced force so that, for instance, a pressure force is translated into a pulling force. The drive unit may also be configured as a transmission gear, which translates a small movement of the moving mechanism into a larger movement of the actuating element or a large movement of the moving mechanism into a small movement of the actuating element. In toothed gearing, the actuating element can have a toothed rack or a toothed wheel, while the actuating element is driven by an additional toothed wheel. Depending on the embodiment, the actuating element moves axially or radially. This provides great freedom of design for optimal adaptation to the site of use of the filter.
In accordance with a further embodiment of the invention, the drive unit can be locked. In this case, the drive unit is provided with an arresting element, which in the engaged state prevents any uncontrolled movement of the drive unit and thus any uncontrolled opening of the water outlet. In the disengaged state, the drive unit can be moved to move the sealing element away from the water outlet and allow accumulated water to escape.
A specific embodiment of the invention provides that the water outlet can be opened and closed automatically, in which case the water discharge device is controlled. One possibility for automation is to connect the water sensor with the actuating element, so that the water can be drained without the intervention of an operator. The water sensor signals, for instance, that the water has exceeded a defined filling level. This causes the actuating element to be moved in its position by the drive mechanism and the sealing element to unblock the outlet opening. After the water falls below a defined minimum filling level, which is defined in such way that no fuel will reach the water outlet, the actuating element is moved back into its closed position, so that the sealing element again seals the water outlet. This reduces manual maintenance.